Ok so I got the PhosBan. I used the little media/filter bag that come with it. It is pretty porous. That had me worried I'd have phosban floating all over my tank. So I put the bag above the return diffuser plate and beneath the sponge. No phosban, that I can notice, falling lower into the chamber, or going thru the sponge into the tank. I'll do a phosphate test tomorrow and trend how my phosphate is. It's been high. Then I'd know if water is flowing through the PhosBan and working. Hoping it does. I'll keep you updated.
Here is a side view of the return chamber while it's running. This is the BH1000 Reef Octopus. I wish I'd looked at this before putting it all back together and running. Looks like I could of spread the PhosBan more evenly.